The present invention assumes a system for accumulating data via the Internet at data generating points dispersed over a wide area, into one data utilization point. One such application system for example is a remote video surveillance system in which cameras installed at plural surveillance points dispersed over a wide area normally capture images for a specified time or 24 hours a day, 365 days a year and by centralized monitoring of those captured images in a (monitoring) center can watch for abnormal situations or objects. These types of video surveillance systems can also in many cases accumulate video data captured by normal camera operation for viewing of that video data later on.
When the system here includes several thousand or even tens of thousands of cameras that are centrally monitored at one center, the problem occurs that simultaneously transmitting the video captured by all cameras to the center is practically impossible to accomplish due to the vast amount of data that must be sent. Moreover, even assuming that the vast amount of video data was sent, other problems immediately arise such as whether there is sufficient memory capacity available for all data that was accumulated or whether the processing load posed by that accumulated video data is excessive.
One extremely practical and effective measure for dealing with these problems is to not transmit all of the captured video. During actual use, the value or importance (priority) level of the camera image varies according to the camera or the image capture time. The value of images captured while an object is moving or images of people for example can be called high importance level images. Conversely, images that show nothing or show no change in an object can be called extremely low importance level images. Moreover, if cameras are installed in specified locations to capture images for example wanted by monitoring personnel, then those images are high importance level camera images. The importance level of the images therefore varies in this way so that just video data having value can be efficiently collected by giving priority to sending of video data with a high importance level and by limiting as much as possible the sending of video data having a low importance level. A further result is that the storage capacity required for accumulating data can be conserved and the load from processing the accumulated video data can be alleviated. This approach is common to accumulating all types of data and not just video data. In view of these circumstances, the non-patent document “Study of Transmission Control Methods for Large Scale Surveillance Systems, The Institute of Electrical Engineers of Japan, CMN-08-14, 2008/5” by the present inventors and others, discloses a video network system and transmission control device for controlling the priority of video data transmissions between plural cameras connected to the same transmission control device, by changing the transmit timing of video data on each connected camera, or the transmission quantity (fps: frames per second) per time unit based on the importance level that the transmission control device installed between the cameras and network attached to the video image, that was calculated using image processing and external sensors.